1. Field of the Invention
This invention relates generally to farming row crop applicators having adjustable track widths, and more specifically, to row crop applicators having an automatic rear axle auto track assembly that follows adjustments of front axle track widths.
2. Description of the Prior Art
Row crop applicators are widely used in the farming industry for applying fertilizer about a field to maximize crop yield. Since different crops are planted in rows having free-selected row widths, depending on the crop to be grown, the row crop applicator machinery needs to have adjustable track widths such that the tires of the applicator can be driven in the rows defined between the rows of crop. Typical row crop applicators have a track width adjustable between 120 and 152 inches.
Four wheeled row crop applicators have a front axle steering assembly including a tie rod extending between a pair of steering structures for maintaining a pre-selected toe-in setting. Consequently, when the track width of the steering assembly is adjusted in the longitudinal direction, the length of the tie rod needs to be adjusted in the longitudinal direction in step therewith. Prior art steering axle assemblies are typically adjusted hydraulically. Most tie rods presently available are typically comprised of a rod telescopingly received within tubular member, wherein a set pin can be selectively removed therefrom such that the inner rod member can telescope within the tubular member when the track width is adjusted such as disclosed in U.S. Pat. No. 4,449,600 to Telfer, issued May 22, 1984 entitled "Mobile Cranes or Aerial Lift Platforms". In those systems, one or more set pins are In those systems, one or more set pins are subsequently reinserted through a pair of holes defined in both the tubular member and the telescoping rod to secure the inner rod to the tubular member. These holes are typically defined in 4 inch increments, wherein the operator has to manually insert and remove the pins during the track width adjustment procedure.
Another major problem with prior art equipment is that the toe-in setting defined by the wheel assemblies needs to be reset whenever the track width is established between a minimum and a maximum setting. Further, since the holes in the tie rod assembly are defined every 4 inches, the operator needs to repeatedly fine tune the track width adjustment until the holes of the inner rod and the outer tubular member are perfectly aligned so that the set pin can be disposed therein. The processes are time consuming, tedious and potentially dangerously as the operator needs to be positioned beneath the front of the tractor chassis. Further, the track width of the row crop applicator can only be adjusted in 4 inch increments and is not adjustable in any size increments between a minimum and a maximum. Some crops are planted in rows as narrow as 24 inches, and since the track widths of tractor wheels can sometimes extend up to 12 inches, a 4 inch track width adjustment increment does not provide adequate fine tuning of a desirable track width.
Typically, independent contractors are hired by the farmer to treat a field. The track width of the contractor's row crop applicator is usually not initially appropriate for the intended field to be treated with fertilizer when the contractor arrives to the field. Thus, the independent contractor is required to adjust the track width and reset the toe-in. Treating several different fields in a day may require setting several different track widths, which is time consuming and inefficient. When the independent contractor is under severe time limitations to treat many fields with a fertilizer in a very narrow time window, which can be dictated by the weather or other uncontrollable circumstances, valuable time is lost during the repeated track width adjustments. Thus, the independent contractor stands to benefit from the present invention. However, even the farm owner can benefit from an improved adjustable tie rod arrangement since the typical farmer plants more than one type of crop, each having different row widths. Hence, having a row crop applicator with an adjustable track width would benefit the average farmer as well, where the track width is adjustable in negligible increments between a minimum and a maximum track width.
A row crop applicator with a steering structure having an adjustable track width in any size increments between a minimum and a maximum, wherein a hydraulically adjustable tie rod can be adjusted in any size increments between a minimum and a maximum track width, while driving the machine, in a secure arrangement between a first and a second track width setting and which overcomes many of the attendant disadvantages of existing systems described hereinbefore, is disclosed in the above-referenced U.S. Pat. No. 5,282,644, assigned to the Assignee of the present invention. Yet, another row crop applicator which overcomes even more of the attendant disadvantages of known systems is disclosed in the above-referenced co-pending U.S. patent application Ser. No. 08/220,237, to Torborg. The automatic tie rod assembly disclosed in Torborg allows the operator to adjust the front track on the go without having to mechanically lock the steering structure. This enables the operator to adjust the front track very accurately for crops in rows, even while spraying a field or turning the vehicle.
For all of the existing systems hereinbefore described, it is easy for the operator to see where the front wheels contact the ground, and adjust the track as required to minimize crop damage accordingly. The operator cannot, however, see where the rear tires contact the ground from the cab. This makes adjusting the rear track very difficult, especially when operating in rows. In some of the existing systems, the operator has to either estimate how long a period of time is necessary to continue adjustment of the rear track assembly or stop the machine and get out of the cab to read a decal or physically examine the rear axle assembly adjustments.
The present invention overcomes the attendant disadvantages heretofore described for existing systems by providing a rear axle auto-track system for automatically ensuring that the rear axle follows the front axle on a vehicle such as a row crop applicator having an adjustable track width.